Shpingosine-1-phosphate (S1P) is a bioactive lipid mediator that interacts with a a family of G-protein coupled receptors. S1P signaling regulates several of the hallmarks of cancer including the induction of angiogenesis, resisting cell death, sustaining proliferative signaling, tumor-promoting inflammation and activating invasion and metastasis. Furthermore, S1P metabolism has been found to be disturbed in several types of tumors providing further support for a linkage between pleiotropic actions of S1P to oncogenesis. We are using novel S1P signaling reporter mice to identify S1P receptor signaling in live mice in response to tumor development, growth and metastasis.